My VPS is a little underpowered, and checking the amount of free memory I was, shall we say, a little surprised at just how much Apache thought it needed for the amount of visitors this domain brings in.
The combination of nginx and php-fpm is astoundingly lightweight on memory usage… with nginx and a seperate process manager for PHP (php-fpm) instead of mod_php I now have a few hundred MB to play with. Not just that but the requests per second my server can now handle is through the roof.
Using phpinfo as a test, I’m now managing to serve 3,000 requests per second at a maximum of 3ms per page.
Even the beastly wordpress is coming in at 1,628 requests per second with a helping hand from APC byte-code cache. Breezy.